# Clinical Course of a Child With Cystic Fibrosis and the Genotype F508del/CFTRdup1_11: A Case Report

## TL;DR

A child with a rare CFTR gene mutation combination shows no symptoms of cystic fibrosis, challenging predictions based on genetic data.

## Contribution

Reports a novel CFTRdup1_11 duplication and its unexpected clinical outcome in a child with cystic fibrosis.

## Key findings

- The child with F508del/CFTRdup1_11 genotype showed no clinical symptoms of cystic fibrosis.
- Sweat chloride concentrations were borderline, not clearly indicative of CF.
- This case highlights the unpredictability of CFTR genotype-phenotype correlations.

## Abstract

Cystic fibrosis (CF) is a hereditary disease with great genetic complexity as not all mutations are disease-causing and genotype doesn’t always predict phenotype. This case involves a child with CF and genotype F508del/CFTRdup1_11. The CFTRdup1_11 duplication was not reported previously, and genetic counseling was based on reports describing the clinical course of people carrying smaller duplications of the same area combined with F508del. The predicted clinical presentation was CF with pancreatic insufficiency. However, the case presented has so far shown no clinical symptoms and has borderline sweat chloride concentrations.